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Thread: Help with speakers and amps

  1. #41
    It's a possibility, the XLR and TRS may be parallel wired. If that's the case you wouldn't need to do any switching. If you have a schematic for the amp it would show it, but you could just try it as a pass through. If it works you're good to go. You wouldn't even need a second amp to test it, just connect the TRS of the two channels with a cable and see if the signal passes to the second channel. If it doesn't work that means the XLR and TRS each have their own input buffer.
    Bill Fitzmaurice
    Bill Fitzmaurice Loudspeaker Design
    www.billfitzmaurice.info/forum

  2. #42
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    Thanks, I haven't worked with amps much so didn't realize that was a possibility, good to know!

  3. #43
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    Quote Originally Posted by shoot summ View Post
    The amp allows you to connect a source to one input(XLR), and the TRS for that input can, or also functions as a passthru? I was looking at the dip switch settings and couldn't see where that was a selection.
    Yes and it's got nothing to do with the switches, the two connectors are simply wired in parallel.
    Paul O'Brien
    Old Tech Guy
    www.Techott.com

  4. #44
    Quote Originally Posted by shoot summ View Post
    I did have a question regarding the wiring, curiosity really. The amp allows you to connect a source to one input(XLR), and the TRS for that input can, or also functions as a passthru? I was looking at the dip switch settings and couldn't see where that was a selection.
    Good question, I've been thinking the same thing at times with some amplifiers (it takes the Y-cable out of the equation)

    You could either check the block diagram/schematic or probe the connectors with a multimeter (once it's turned off, though).. like Bill said they could have their own input buffering but in practice the chances of finding a "matched" pair of opamps are thin (ie. they vary in their parameters, the sound/volume/noise characteristics are or could be different depending on which connector you use) although if the one in use goes off there's another which could still be functioning (kind of a long shot, shorting an opamp may cause all kinds of issues anyway)

    They're very likely made to accept line level (ie. you can't use a microphone, guitar etc low-level source plugged directly into the amp, some active speakers and mixers have separate mic, hi-z or line inputs for this) from a mixer.

    Another thing is they could be switching connectors that break the connection when you plug in (ie. you'd probe them with a cable or open the amp)

    As it is, from what I understood a 2nd hand system I'd ask the original owner whether it's been modified or something (and how it was ran in the first place)

  5. #45
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    Here is a clip from the RMX schematic, as mentioned the input connectors J101 and J102 are simply connected together in parallel, when there are secondary input connectors on an amplifier this is the case in every one I have seen. This often is not the case on other types of equipment but that isn't part of this discussion.

    [IMG]RMX Input by paul, on Flickr[/IMG]
    Paul O'Brien
    Old Tech Guy
    www.Techott.com

  6. #46
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    Quote Originally Posted by conanski View Post
    Here is a clip from the RMX schematic, as mentioned the input connectors J101 and J102 are simply connected together in parallel, when there are secondary input connectors on an amplifier this is the case in every one I have seen. This often is not the case on other types of equipment but that isn't part of this discussion.

    [IMG]RMX Input by paul, on Flickr[/IMG]
    Absolutely makes sense, just had never really thought it through.

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